1. Field of the Invention
The invention relates generally to handheld electronic devices and, more particularly, to a handheld electronic device executing an application which employs a keystroke interpretation system. The invention further relates to methods of automatically selecting the language that the keystroke interpretation system utilizes.
2. Background Information
Numerous types of handheld electronic devices are known. Examples of such handheld electronic devices include, for instance, personal data assistants (PDAs), handheld computers, two-way pagers, cellular telephones, and the like. Many handheld electronic devices also feature wireless communication capability, although many such handheld electronic devices are stand-alone devices that are functional without communication with other devices.
Such handheld electronic devices are generally intended to be portable, and thus are of a relatively compact configuration in which keys and other input structures often perform multiple functions under certain circumstances or may otherwise have multiple aspects or features assigned thereto. With advances in technology, handheld electronic devices are built to have progressively smaller form factors yet have progressively greater numbers of applications and features resident thereon. As a practical matter, the keys of a keypad can only be reduced to a certain small size before the keys become increasingly unusable. In order to enable text entry, however, a keypad must be capable of entering all twenty-six letters of the Latin alphabet, for instance, as well as appropriate punctuation and other symbols.
One way of providing numerous letters in a small space has been to provide a “reduced keyboard” in which multiple letters, symbols, digits, and the like, are assigned to any given key. For example, a touch-tone telephone includes a reduced keyboard by providing twelve keys, of which ten have digits thereon, and of these ten keys, eight have Latin letters and symbols assigned thereto. For instance, one of the keys includes the digit “2” as well as the letters “A”, “B”, and “C”. Since a single actuation of such a key potentially could be intended by the user to refer to any of the letters “A”, “B”, and “C”, and potentially could also be intended to refer to the digit “2”, the input (by actuation of the key) generally is an ambiguous input and is in need of some type of disambiguation in order to be useful for text entry purposes. Other known reduced keyboards have included other arrangements of keys, letters, symbols, digits, and the like.
In order to enable a user to make use of the multiple letters, digits, and the like on any given key in an ambiguous keyboard, numerous keystroke interpretation systems have been provided. For instance, a “multi-tap” system allows a user to substantially unambiguously specify a particular character on a key by pressing the same key a number of times equivalent to the position of the desired character on the key. For example, on the aforementioned telephone key that includes the letters “ABC”, if the user desires to specify the letter “C”, the user will press the key three times.
Another exemplary keystroke interpretation system would include key chording, of which various types exist. For instance, a particular character can be entered by pressing two keys in succession or by pressing and holding a first key while pressing a second key. Still another exemplary keystroke interpretation system would be a “press-and-hold/press-and-release” interpretation function in which a given key provides a first result if the key is pressed and immediately released, and provides a second result if the key is pressed and held for a short period of time.
Another keystroke interpretation system that has been employed is a software-based text disambiguation function. In such a system, a user typically presses keys to which one or more characters have been assigned, generally pressing each key one time for each desired letter, and the disambiguation software attempts to determine the intended input. Numerous such systems have been proposed. One example of such a system is disclosed in commonly owned U.S. patent application Ser. No. 10/931,281, entitled “Handheld Electronic Device With Text Disambiguation,” the disclosure of which is incorporated herein by reference.
As will be appreciated, certain of the keystroke interpretation systems described above (“multi-tap,” chording, and “press-and-hold/press-and-release”) rely on the number of times that a key is actuated, the number of keys that are actuated, and/or how long that a key remains actuated, each of which constitute a non-ambiguous key actuation sequence, to ascertain, with certainty, the intended input. Such systems do not attempt to determine an intended input using an ambiguous input like software-based text disambiguation function systems do. Such keystroke interpretation systems (“multi-tap,” chording, and “press-and-hold/press-and-release”) shall be referred to herein as “determinative keystroke interpretation systems.”
Handheld electronic devices that incorporate a probabilistic keystroke interpretation system such as a software-based text disambiguation function system may encounter additional difficulty during text entry in different languages. In an email application, for example, a user may send a first message to all French speaking recipients in French and a subsequent message to all German speaking recipients in German. The system may operate in an undesirable fashion because it does not know whether a given ambiguous input is intended to represent a French word or a German word.
Thus, a need exists for a handheld electronic device which employs a keystroke interpretation system and which facilitates text entry in multiple languages.